The goal of this proposal is to construct a clinically reliable ultrasound scanner which can obtain quantitative images of several acoustical parameters within two-dimensional cross-sections of the breast of patients in a period of a few minutes. The instrument will combine these quantitative multimodal images to obtain a synergistic effect resulting in a high probability of obtaining differential diagnosis of breast disease. Ultrasound computer-assisted transmission tomography will be utilized to obtain quantitative cross-sectional images of acoustic speed, acoustic attenuation, acoustic absorption and scatter and reflection where appropriate. Synthetic aperture imaging and compound B-scan techniques will be utilized to obtain high resolution images of the distribution of echoing interfaces within each studied plane of the breast. Aberrations in the images caused by inhomogeneous distributions of acoustic speed will be corrected by techniques currently under development in this laboratory. A clinical trial will be conducted in which patients scheduled for surgical biopsy will be scanned by the ultrasound scanner and the resulting images compared to the results of the biopsy and/or surgical mastectomy. Comparisons between surgical specimens and acoustic images will be made using methods of automated computer-assisted pattern classification and recognition combined with histological methods of tissue preparation specifically designed to aid in comparing the ultrasound images of the coronal plane of the intact breast with similar planes through the excised breast. This parallel development of the clinical instrument, the tissue analysis technique, and the pattern recognition programs should result in complete evaluation of a prototype clinical instrument which could be used in the high volume clinical environment.